The highest speed limits are generally 75 mph (121 km/h) in western states and 70 mph (113 km/h) in eastern states. A few states, mainly in the Northeast Megalopolis
, have 65 mph (105 km/h) limits, and Hawaii only has 60 mph (97 km/h) maximum limits. A small portion of the Texas
road networks have 80 mph speed limits. While parts of Louisiana
are located east of the Mississippi River
, 75 mph limits are only posted west of the Mississippi River. Therefore, Maine
is the only state completely east of the Mississippi River to have a maximum speed limit of 75 mph.